Pen/touch tablet computer having multiple operation modes and method for switching operation modes

ABSTRACT

A tablet computer is provided, which includes a sensor section operable to detect positional input by a human operator and output a positional input signal; a display, laid over the sensor section, operable to receive and display a video signal; and a processor, coupled to a memory storing programs for running an operating system (OS) and executing software loaded to the memory, the processor being operable to receive and process the positional input signal from the sensor section and to output a video signal of the OS and the software to the display. The tablet computer further includes a sensor signal filter capable of selectively communicating the positional input signal from the sensor section to the processor, to a separate external processor, or to neither the processor nor the separate external processor; and a display switch capable of coupling the display to the processor or to the separate external processor.

BACKGROUND Technical Field

The present invention relates to a tablet computer capable of beingcoupled to an external computer, and specifically to such tabletcomputer capable of switching its operation modes when coupled to anexternal computer.

Description of the Related Art

(1) Graphics Tablet (Digitizer) and Pen Display

A graphics tablet or a digitizer is widely used among users who wish tocreate hand-drawn images and graphics on a computer, similar to the waya person draws images with a pencil and paper. A typical graphics tabletincludes a flat surface, upon which the user may “draw” or trace animage using a stylus or a pen-like drawing implement. The imagegenerally does not appear on the tablet itself but, rather, is displayedon the monitor of an external computer, to which the graphics tablet isconnected.

Some graphics tablets incorporate an LCD screen into the tablet itselfsuch that the user's hand-drawn images appear on the tablet itself.These devices are called pen displays, one example of which is theCintiq® line of pen displays available from WACOM®. A pen display allowsthe user to draw directly on the display surface. A pen display isrequired to be connected, via a wired or wireless connection, to anexternal computer having greater computational resources, such asgreater processing power of CPU or GPU or memory capacity. A pen displayutilizes the processing power of an external computer, and iscategorized as a dependent or peripheral device of the externalcomputer.

(2) Mobile Tablet Computer

On the other hand, in a mobile computer world, a mobile tablet computerincluding a CPU, memory, and a touch/pen sensor with a display has beenwidely used. A tablet computer, which may run on battery power and whoseprocessor is controlled by its own operating system (OS), is originallydesigned to be used independently of other computers (“mobile mode”). Auser of such tablet computer may utilize a positional input sensor,typically a touch sensor, to interact with the OS and applicationsoftware to, for example, send emails or surf the web. A tabletcomputer's processor, in part due to its compact size, is ofteninadequate for carrying out computationally intensive processing such asgraphics data processing.

BRIEF SUMMARY

It is possible to couple a tablet computer to a dedicated externalprocessor so as to utilize the full processing power of the externalprocessor controlled by its own OS different from the tablet computer'sOS (“desktop mode”).

When a tablet computer is coupled to an external processor, it isdesirable to optimize the allocation of computational resources (CPUs,LCD, UI, battery, storage area) between the two computers. To that end,having just desktop mode whenever a tablet computer is coupled to anexternal processor may be insufficient. A need exists for a tabletcomputer capable of switching between multiple operation modes whencoupled to an external processor.

Typically a tablet computer includes numerous operable devices, such asa positional input sensor (a pen sensor and/or a touch sensor), adisplay, a storage device (memory), a camera, a microphone, a speaker,etc., and a user may wish to keep one or more of these devices under thecontrol of the tablet computer's own OS, as opposed to having themaccessible or controllable by the external processor's OS. In othercases, the user may wish to even disable one or more of these devicesaltogether, for example, to save battery power of the tablet computer,because a tablet computer typically continues to operate on batterypower even after it is coupled to an external processor. Therefore, aneed exists for a tablet computer capable of switching operation modesof its devices, such as a pen/touch input sensor, when the tabletcomputer is coupled to an external processor.

According to one aspect of the invention, a tablet computer is provided,which includes a sensor section operable to detect positional input by ahuman operator and output a positional input signal; a display, laidover the sensor section, operable to receive and display a video signal;and a processor, coupled to a memory storing programs for running anoperating system (OS) and executing software loaded to the memory. Theprocessor is operable to receive and process the positional input signalfrom the sensor section and to output a video signal of the OS and thesoftware to the display. The tablet computer further includes a sensorsignal filter capable of selectively communicating the positional inputsignal from the sensor section to the tablet computer processor, to aseparate external processor, or to neither the tablet computer processornor the separate external processor. The tablet computer still furtherincludes a display switch capable of coupling the display to the tabletcomputer processor or to the separate external processor.

The tablet computer according to such configuration is capable ofswitching operation modes of the position input sensor (e.g., pen/touchsensor) and the display when the tablet computer is coupled to anexternal processor.

According to a further aspect of the invention, the tablet computerprocessor controls the sensor signal filter (e.g., a three-way switch)and the display switch (a two-way switch) to automatically switchoperation modes of the sensor and the display based on a video-in linkstatus and a data link status of the tablet computer relative to theseparate external processor. For example, upon detecting that thevideo-in link exists but the data link does not exist relative to theseparate external processor (i.e., the tablet computer is partiallycoupled to the external processor via the video-in link only), thetablet computer processor controls the display switch to couple thedisplay to the separate external processor and controls the sensorsignal filter to not communicate the positional input signal to eitherthe tablet computer processor or the separate external processor. As aresult, the tablet computer functions as a monitor for the externalprocessor, i.e., operates in “monitor mode” according to variousembodiments of the present invention.

According to another aspect of the invention, a method of switchingoperation modes of a tablet computer is provided. The method includesgenerally three steps: (i) detecting a video-in link status of thetablet computer relative to a separate external processor; (ii)detecting a data link status of the tablet computer relative to theseparate external processor; and (iii) when the video-in link exits butthe data link does not exist relative to the separate externalprocessor, displaying a video signal from the separate externalprocessor on a tablet display and not communicating the positional inputsignal from a tablet sensor to either the tablet computer processor orthe separate external processor. The last step entails operating thetablet computer in monitor mode.

According to a further aspect of the invention, a tablet computer isprovided, which is capable of being coupled to an external computerwirelessly or via a single cable. The tablet computer includes a sensorsection operable to detect a positional input by a human operator andoutput a positional input signal; a display that is laid over the sensorsection and is operable to receive and display a video signal; and aprocessor that is coupled to a memory storing programs for running anoperating system (OS) and executing software loaded to the memory andthat is operable to receive and process the positional input signal fromthe sensor section and to output a video signal of the OS and thesoftware to the display. The tablet computer also includes one or moredevices coupled to the processor and operable to transfer data with theprocessor. The processor includes a controller configured to controlexecution of the following generally six steps: (i) establishing avideo-in link for the tablet computer (for the tablet display) from aseparate external processor; (ii) establishing a data link between atleast one of the sensor section and the one or more devices of thetablet computer and the separate external processor; (iii) establishinga command link with the separate external processor; (iv) sending amode-switching user interface (UI) message to the separate externalprocessor via the command link to cause the separate external processorto display a mode-switching UI on the tablet display, the mode-switchingUI including at least one user-selectable element to control operationof at least one of the sensor section and the one or more devices of thetablet computer; (v) receiving user selection of the at least oneuser-selectable element on the tablet display, made via an externalinput device connected to the separate external processor (or via thesensor section, if not disabled), as a UI-entry message from theseparate external processor via the command link; and (vi) controllingoperation of the corresponding device based on the received UI-entrymessage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A and 1B each illustrate an example tablet computer coupled to anexternal processor.

FIGS. 2A-2D illustrate operation modes of a tablet computer coupled toan external processor, including “desktop mode,” “tethered mode,” and“monitor mode.”

FIGS. 3A and 3B are block diagrams each illustrating an exampleconfiguration of a tablet computer coupled to an external processor,according to some embodiments of the present invention.

FIG. 3C is a block diagram of an example configuration of a flow controldevice and a 2-to-1 switch, which allows for various operational modesswitching of a tablet sensor.

FIG. 4 is a block diagram of another sample configuration of a tabletcomputer coupled to an external processor wirelessly or via a singlecable, according to other embodiments of the present invention.

FIGS. 5A and 5B are each a flowchart illustrating an example process ofswitching operation modes of a tablet computer coupled to an externalprocessor.

FIGS. 5C and 5D are diagrams illustrating transitions among fouroperational modes and three operational modes, respectively, of a tabletsensor according to various embodiments.

FIG. 6 is a flowchart illustrating another example process of switchingoperation modes of a tablet computer coupled to an external processor,suitable for execution in a tablet computer coupled to an externalprocessor wirelessly or via a single cable.

DETAILED DESCRIPTION

FIGS. 1A and 1B each illustrate an example tablet computer 10 coupled toan external processor 18. As more fully described below, the tabletcomputer 10 includes a positional input sensor such as a pen sensor, atouch sensor, or a combination of a pen sensor and a touch sensor, whichis operable to detect positional input by a human operator and to outputa positional input signal. The tablet computer 10 also includes adisplay, laid over the sensor section, operable to receive and display avideo signal. The tablet computer 10 may further include additional(peripheral) devices such as a storage device (memory), a camera, amicrophone, a speaker, etc. Though not specifically illustrated, boththe tablet computer 10 and the external processor 18 have a power inputport, and additionally at least the tablet computer 10 includes abattery to be operable in mobile mode. According to various embodimentsof the present invention, when the tablet computer 10 is coupled to theexternal processor 18, one or more of the operable devices of the tabletcomputer 10, such as the positional input sensor, may be selectivelydisabled or left under the control of the tablet computer 10's operatingsystem (OS).

FIG. 1A shows the tablet computer 10 coupled to the external processor(CPU) 18, which is part of a desktop computer 12 including a display 14(optional) and an input device 16 (optional), such as a keyboard with atouchpad, as shown, and/or a keyboard, a touchpad, a mouse, a trackball,a pen and/or touch input sensor, etc. As used herein, the terms externalprocessor and external computer are used mostly interchangeably, as willbe apparent from the context of the description. Those skilled in theart would readily recognize that a processor connecting via standardvideo or data links to other devices is typically integrated into acomputer, although in theory a direct connection is also possible. FIG.1B shows the tablet computer 10 coupled to the external processor 18built within a laptop computer 12A, which also includes a built-indisplay 14 and a built-in input device 16 such as a keyboard with atouchpad, as shown. According to various exemplary embodiments, oneadvantage of the present invention is that the tablet computer 10 can becoupled to any generic external processor operating on any standard OS,such as a PC operating on Microsoft Windows® OS, and any processoroperating on Mac® OS, Linux® OS, and other standard OSs. In order toattain this advantage, the tablet computer 10, not an externalprocessor, is responsible for controlling transitions between variousoperation mode when coupled to the external processor. Any additional,non-standard software or hardware implementations are not required inthe external processor in various embodiments of the present invention.

In some embodiments, as shown in FIG. 1A, the tablet computer 10 iscoupled to the external processor 18 via a combination of a data line20A such as a USB cable, and a video line (or a multimedia line) such asan HDMI (High Definition Multimedia Interface) cable 20B. This isbecause a generic external processor 18 and computer 12 typicallyinclude two physically separate data and video ports, such as, e.g., aUSB port and a HDMI port.

In other embodiments, as shown in FIG. 1B, a data line and a video linemay be combined into one line to be received at a single physical portprovided for the external processor 18 in the notebook computer 12A, inwhich case a single cable 20C (e.g., Thunderbolt® cable) may be used tocouple the tablet computer 10 to the external processor 18. In stillfurther embodiments, a wireless connection 20D (e.g., Bluetooth®, a USBprotocol data encapsulated in frame IEEE 802.11a/b/g/n, WiHD(WirelessHD™) or a similar technology) may be used to couple the tabletcomputer 10 to the external processor 18 and computer 12 to substitutethe respective wired technologies.

When the tablet computer 10 is coupled to the external processor 18 andcomputer 12 via a single cable connection 20C or a wireless connection20D, through which all of the lines (e.g., the data line, the videoline, a command line, etc.) are connected or disconnected at the sametime, a user is given the ability to selectively connect or disconnectone or more of these lines to effect operation mode switching for thetablet computer 10, as will be more fully described below in referenceto FIG. 4.

In this specification, the word “connected,” “coupled,” “communicate,”or “link” with regards to the input (e.g., pen/touch) sensor signalinterface includes at least the following meanings: (1) an electricsignal is detected between physical layers of the input sensor and ahost processor (the tablet processor or the external processor); (2) ahandshake procedure is initiated between the input sensor and a hostprocessor (e.g., a USB handshake between MAC layers of the input sensorand a host processor); (3) a logical pipe is established between theinput sensor and a host processor; and (4) an electric signal isdetected between physical layers associated with the input sensor and ahost processor (e.g., in the case of USB connections, an electric signalbeing detected between physical layers of the next-hop node of the inputsensor in a USB network and a host processor).

In this specification, the word “connected,” “coupled,” or “link” withregards to the display interface includes at least the followingmeanings: (1) an electric signal is detected between physical layers ofthe display and a host processor (the tablet processor or the externalprocessor); (2) an association is established between the display and ahost processor; and (3) a display data transfer process is establishedbetween the display and a host processor. FIGS. 2A-2D illustrate fourdifferent operation modes of the tablet computer 10, including “mobilemode” when the tablet computer 10 is not coupled to an externalprocessor, and three other modes (“monitor mode,” “tethered mode,” and“desktop mode”) when the tablet computer 10 is coupled to the externalprocessor 18 in computer 12/12A.

FIG. 2A shows the tablet computer 10 in “mobile mode,” wherein thetablet computer 10 is not coupled to any external processor. The tabletcomputer 10 includes a built-in tablet processor 28 running a suitableOS (e.g., Android® OS, iOS®, Windows® Mobile OS, etc.), a positionalinput sensor 30 such as a pen sensor and/or a touch sensor, and adisplay 32 laid over the positional input sensor 30.

The position input sensor 30 is operable to detect positional input madeby a human operator using a pen and/or a finger, and output a positionalinput signal indicative of a position pointed to by the operator. Apositional input sensor may be a pen sensor configured to detect aposition of a pen (stylus) relative to a sensor surface, or a touchsensor configured to detect a position of a finger relative to a sensorsurface, or a combination of a pen sensor and a touch sensor. Variouspen sensors are known such as those based on electromagnetic couplingbetween an X-Y matrix of line electrodes arranged on a sensor surfaceand a resonant circuit provided in a pen. Various touch sensors areknown such as a capacitive type sensor configured to detect a fingertouch at an intersection between an X electrode and a Y electrode in anX-Y sensor matrix as a change in capacitance between the X and Yelectrodes.

The display 32 is laid over the positional input sensor 30 and isoperable to receive and display a video signal. As used herein, a videosignal includes a video signal and an image signal, digital or analog(e.g., Low-voltage differential signaling (LVDS), Display Port (DP),Internal DisplayPort (iDP), Digital Visual Interface (DVI), analog RGBsignals, or similar), and may be part of a multimedia signal includingboth video and audio signals (e.g., HDMI or WirelessHD, or similarsignals). In some cases, it is possible to use different types ofsignals. For example, a video-out link may be in compliance with a firstsignal type (e.g., LVDS) while a video-in link may be in compliance witha second signal type (e.g., HDMI). In these cases, a translator isincluded that is configured to convert one of the video signal types tothe other type. The translator may then include a video signal sensor40, to be described below, which detects an incoming video signal fromthe external processor 18 and sends a video-in link status signal at aproper timing pursuant to the relevant video signal type.

The display 32 may be an LCD (Liquid Crystal Display), organic EL(Electro Luminescence) display, or any other suitable display or screenthat can be used with the positional input sensor 30.

The relative positions of the tablet processor 28, the positional inputsensor 30, and the display 32 are not limited to what is illustratedand, for example, the positional input sensor 30 made of substantiallytransparent material may be placed on top of the display 32 if a usercan view the display 32 through the positional input sensor 30.

In mobile mode as shown in FIG. 2A, the positional input signal from thesensor 30 is sent to the tablet processor 28, and the tablet processor28 sends a video signal to the display 32. The tablet processor 28 iscoupled to a memory storing programs for running a tablet OS (e.g.,Android® OS, iOS®) and executing any software loaded to the memory. Thetablet processor 28 receives the positional input signal for the tabletOS and the software and outputs a video signal of the tablet OS and thesoftware to the display 32.

FIG. 2B shows the tablet computer 10 in “monitor mode,” wherein avideo-in link 36 is established for the display 32 to receive a videosignal from the external processor 18, but the positional input signalfrom the sensor 30 is not sent to either the tablet processor 28 or theexternal processor 18. As a result, the positional input signal of thesensor 30 is ignored and, hence, the tablet computer 10 essentiallyfunctions as a monitor display for the external processor 18, which mayor may not include its own display 14 (see FIGS. 1A and 1B). Monitormode of operating the tablet computer 10 coupled to the externalprocessor, in which the position input sensor 30 is essentiallydisabled, is one aspect of the present invention as will be more fullydescribed below.

FIG. 2C shows the tablet computer 10 in “tethered mode,” wherein thedisplay 32 receives a video signal from the tablet processor 28 and thepositional input signal from the sensor 30 is sent to the tabletprocessor 28, similar to mobile mode, but a data link (e.g., a USB link)38 is established between the tablet processor 28 and the externalprocessor 18 such that data can be exchanged between the two processors(as well as between the memories of the two computers 10 and 12).

FIG. 2D shows the tablet computer 10 in “desktop mode,” wherein both thevideo-in link 36 and the data link 38 are established between the tabletcomputer 10 and the external processor 18 and computer 12. The display32 is coupled to the external processor 18 via the video-in link 36 toreceive a video signal therefrom. As shown, in various embodiments, thetablet computer 10 includes a data flow control device 34, such as a USBhub, in order to control various data flows used in or for the tabletcomputer 10. In the illustrated embodiment, the positional input signalfrom the sensor 30 is sent via data flow control device 34 on the datalink 38 to the external processor 18. Other data may also be exchangedbetween the tablet processor 28 and the external processor 18 on thedata link 38.

Referring back to FIG. 2B, monitor mode of operating the tablet computer10 is advantageous in that a user may selectively disable the positioninput sensor 30, to thereby use the tablet computer 10 as a monitor forthe external processor 18/computer 12.

There are at least two advantages associated with the functionality todisable the position input sensor 30. First, it prevents a user, who isviewing the display displaying a video signal from the externalprocessor 18/computer 12, from attempting to operate the sensor 30 thatis decoupled from what is shown on the display. This can prevent, forexample, a situation in which the user operates the sensor 30 to try tomove a folder from one location to another on the external computer'sdesktop, but instead inadvertently provides input to the internalcomputer's desktop (not shown on the display) creating random results(including file deletions or corruptions) on the internal computer'sdesktop. Second, the functionality is advantageous to save battery powerof the tablet computer because a tablet computer may continue to operateon battery power even after it is coupled to an external processor. Inaccordance with further aspects of the present invention, switching toand from monitor mode may be done intuitively, either automatically(without user selection of any switch) or semi-automatically (with userselection of a UI software switch), as will be more fully describedbelow.

FIG. 3A is a block diagram illustrating an example configuration of thetablet computer 10 coupled to an external processor 18. The tabletcomputer 10 is configured to be operable to switch into and out ofmonitor mode of operation automatically (without user selection of anyswitch). Briefly, the automatic switching is done by the tabletprocessor controller detecting the tablet computer's video-in linkstatus and data link status relative to the external processor 18 andentering into monitor mode if the video-in link exists but the data linkdoes not exist. In monitor mode, the tablet computer 10 displays a videosignal from the external processor 18 on the display 32, withoutcommunicating the positional input signal from the sensor 30 to eitherthe tablet processor 28 or the external processor 18, therebyessentially disabling the sensor 30.

FIG. 3A shows that the tablet computer 10 includes the positional inputsensor 30 (e.g., a pen sensor, a touch sensor, or a combinationthereof), the display 32 laid over the sensor 30, and the tabletprocessor 28 coupled to a memory 44 storing programs for running atablet OS and executing software loaded to the memory 44. The tabletcomputer 10 also includes a sensor signal filter 46 in the form of athree-way switch in the illustrated embodiment, and further includes adisplay switch 48. The sensor signal filter 46 is configured to becapable of selectively communicating the positional input signal fromthe sensor 30 to a sensor signal interface 47 (e.g., USB interface) ofthe tablet processor 28, to a sensor signal interface 49 (e.g., USBport) of the external computer 12 containing the external processor 18(through an interface connector in the data cable 20A, see FIG. 1A), orto neither the tablet processor 28 nor the external processor 18, i.e.,to an OFF terminal provided in the three-way switch. As used herein, notcommunicating the positional input signal to neither of the processors(OFF terminal) refers to a state in which the positional input signal isnot used for its intended function. For example, the OFF terminal stateincludes a situation wherein there is no signal output from the sensorsignal filter 46, and a situation where any signal output therefrom isignored by the controller.

The display switch 48 is configured to be capable of coupling thedisplay 32 to a video signal interface 52 (e.g., HDMI interface) of thetablet processor 28 or to a video signal interface 54 (e.g., HDMI port)of the external processor 18 (through an interface connector in thevideo cable 20B, see FIG. 1A). As in the illustrated embodiment, thetablet computer 10 may employ standard interface connectors to connectto standard interface ports, such as the USB port 49 and the HDMI port54 typically provided for a standard processor, which permits couplingof the tablet computer 10 to any generic external computer 12 containingprocessor 18.

A controller 50 of the tablet processor 28 controls the sensor signalfilter 46 and the display switch 48 based on a detected video-in linkstatus relative to the external processor 18 and based on a detecteddata link status relative to the external processor 18. In theillustrated embodiment, the tablet computer 10 includes a video signalsensor 40 and a data signal sensor 42, which are respectively configuredand arranged to detect the video-in link status and the data link statusof the tablet computer 10 relative to the external processor 18 and tosend detection signals to the controller 50. In FIG. 3A, detectionsignals that the controller 50 receives, as well as control signals thatthe controller 50 issues to control the sensor signal filter 46 and thedisplay switch 48, are shown in dashed-line arrows.

The video signal sensor 40 is arranged between the display switch 48 andthe external processor 18. When it detects an incoming video signal fromthe external processor 18, for example, it sends a video-in link statussignal to the controller 50 to indicate that the video-in link with theexternal processor 18 exists. The data signal sensor 42 is arrangedbetween the signal sensor filter 46 and the external processor 18. Whenit detects no data signal from the external processor 18, for example,it sends a data link status signal to the controller 50 to indicate thatthe data link with the external processor 18 does not exist. Thecontroller 50, upon detecting a video-in link status change (that thevideo-in link exists) and using the detected video-in link status changeas a trigger, when the data link does not exist with the externalprocessor 18, issues a sensor switch control signal to the sensor signalfilter 46 to select the OFF terminal so that the positional input signalfrom the sensor 30 is not communicated to either the tablet processor 28or the external processor 18. Also using the detected video-in linkstatus change as a trigger, at the same time, the controller 50 issues adisplay switch control signal to the display switch 48 to select orconfirm that the display 32 is coupled to the external processor 18. Forexample, if the tablet computer 10 was previously in tethered mode (seeFIG. 2C), the display switch 48 needs to switch the connection to couplethe display 32, previously connected to the tablet processor 28, to theexternal processor 18. If the tablet computer 10 was previously indesktop mode (see FIG. 2D), the display switch 48 maintains theconnection to continue coupling the display 32 to the external processor18.

Thus, for example, when the user has the tablet computer 10 in desktopmode with both the data (e.g., USB) cable 20A and the video (e.g., HDMI)cable 20B connected to the external processor 18, and the userdisconnects only the data cable 20A, the controller 50 detects that thevideo-in link exists but the data link does not exist and issuescorresponding switch control signals. Accordingly, the tablet computer10 automatically transitions from desktop mode to monitor mode.

As another example, when the user has the tablet computer 10 in monitormode, with only the video cable 20B connected to the external processor18, and the user additionally connects the data cable 20A to theexternal processor 18, the controller 50 detects that both the video-inlink and the data link exist and issues corresponding switch controlsignals. Accordingly, the tablet computer 10 automatically transitionsfrom monitor mode to desktop mode.

Other transitions to and from monitor mode, as well as furthertransitions amongst different modes of operation of the tablet computer10, are also automatically implemented by the controller 50 using thedetected video-in link status change as a trigger and based on a statusof the data link with the external processor 18.

In some embodiments, a state in which the positional input signal is notoutput or communicated includes a configuration in which a device driverfor the sensor 30 is disabled. In these cases, by disabling theprocessing in the device driver, no sensor pointer is displayed on thedisplay, thereby preventing a user from attempting to operate the sensor30.

In some embodiments, in monitor mode when the controller 50 controls thesensor signal filter 46 to not communicate the positional input signalfrom the sensor 30 to either the tablet processor 28 or the externalprocessor 18, the controller 50 may additionally issue a control signalto disable (deactivate) the sensor 30 so that the sensor 30 does notgenerate the positional input signal. This arrangement is advantageousin achieving further battery power saving, for example.

As shown in FIG. 3A, the tablet computer 10 may still further include aspeaker 56 operable to receive and play an audio signal. When the videosignal from the external processor 18 or from the tablet processor 28 isa multimedia signal including both video and audio signals, such as anHDMI signal, the display switch 48 serves to couple both the display 32and the speaker 56 to either the external processor 18 to receive videoand audio signals therefrom, or the tablet processor 28 to receive videoand audio signals therefrom.

In other embodiments, where a translator configured to convert the HDMIsignal including video and audio to a different video type such as LVDSis configured with the video signal sensor 40, the translator mayseparate audio from video, and input the audio directly or via a decoderto the speaker 56, while inputting the separate video only to the switch48.

The tablet computer 10 may still further include a data flow controldevice 34, such as a data aggregating hub, arranged between the sensor30 and the sensor signal filter 46 (e.g., the three-way switch). Whenthe data flow control device 34 is provided, and various devices of thetablet computer 10 as well as the sensor 30 are coupled thereto, thesensor signal filter 46 may operate to switch the communication statesof all of these devices and the sensor 30 at the same time. The otherdevices may include, for example, other input/output devices such as aUSB jack 58, to which other USB-connected devices 60 such as a mouse, aUSB drive, etc., may be connected, and other peripheral devices 62 suchas a camera and a microphone. The tablet computer 10 may further includeother system devices 66, such as memory for the OS and data files 44, abattery charging circuit, a GPS sensor, a Bluetooth® module, that aredirectly connected to the processor 28, the data of which may beprovided to an external computer 12 via a USB-Client interface 64. Asshown in FIG. 3A, all of these other devices and the sensor 30 areconnected to downstream ports of the data flow control device 34 (e.g.,data aggregating hub), which is in turn connected at its upstream portto the sensor signal filter 46. Thus, the controller 50 may control theconnection states of the sensor signal filter 46 to communicate all ofthe signals from the various devices (except the directly connecteddevices 66) and the sensor 30 to (and with) the tablet processor 28, to(and with) the external processor 18, or to the OFF terminal at the sametime. The ability to essentially disable all of these devices and thesensor 30 at the same time, by coupling them all to the OFF terminal,may be advantageous in achieving further power saving during monitormode.

FIG. 3B is a block diagram illustrating another embodiment of a tabletcomputer 10A coupled to an external processor 18, wherein the likecomponents and elements are labeled and numbered the same as in theprevious embodiment shown in FIG. 3A. The embodiment of FIG. 3B differsfrom that of FIG. 3A in that its sensor signal filter, configured toselectively communicate the positional input signal from the sensor 30to the tablet processor 28, the external processor 18, or neither thetablet processor 28 nor the external processor 18, is formed of acombination of a two-way switch 68 and a data flow control device 34A,such as a data aggregating and filtering hub (e.g., USB hub). Thetwo-way switch 68 is configured and arranged to selectively communicatethe positional input signal from the sensor 30 to the sensor signalinterface 47 (e.g., USB interface) of the tablet processor 28 or to adownstream port 43A of the data flow control device 34A. The data flowcontrol device 34A (e.g., USB hub) is operable to select betweencommunicating or not communicating (filtering) the positional inputsignal received via the downstream port 43A from the two-way switch 68to the external processor 18 via an upstream port 43B. For example, theUSB hub is operable to turn off its flow control function when detectingno data traffic coming to the upstream port 43B from the externalprocessor 18 (e.g., when the upstream port 49 is found to bedisconnected). Thus, the upstream port 43B of the USB hub 34Aessentially functions as an internal data signal sensor (see 42 in FIG.3A) which, when detecting no data traffic from the external processor18, may determine that the data link with the external processor 18 doesnot exist.

In operation, when the user has the tablet computer 10A in mobile modewith both the data (e.g., USB) cable 20A and the video (e.g., HDMI)cable 20B disconnected from the external processor 18 (see FIG. 2A), andthe user connects only the video cable 20B, the video signal sensor 40sends to the controller 50 a video-in link status signal indicating thata video-in link with the external processor 18 exists. The controller50, thus determining that the video-in link exists with the externalprocessor 18, issues a sensor switch control signal to the two-wayswitch 68 to switch the connection to couple the sensor 30, previouslyconnected to the tablet processor 28, to the downstream port 43A of thedata flow control device 34A (which essentially serves as an OFFterminal because the data flow control device 34A has turned off itsflow control function). At the same time, the controller 50 issues adisplay switch control signal to the display switch 48 to switch theconnection to couple the display 32, previously connected to the tabletprocessor 28, to the external processor 18. Thus, the tablet computer10A transitions from mobile mode to monitor mode automatically based ondetected statuses of the video-in link and the data link with theexternal processor 18.

As another operational example, when the tablet computer 10A is inmonitor mode with only the video cable 20B connected to the externalprocessor 18, and the user disconnects the video cable 20B from theexternal processor 18, the tablet computer 10A automatically transitionsfrom monitor mode back to mobile mode. Specifically, the video signalsensor 40 sends to the controller 50 a video-in link status signalindicating that a video-in link with the external processor 18 does notexist. The controller 50, thus determining that the video-in link withthe external processor 18 does not exist any longer, issues a sensorswitch control signal to the two-way switch 68 to switch the connectionto couple the sensor 30, previously connected to the downstream port 43Aof the data flow control device 34A, to the tablet processor 28. At thesame time, the controller 50 issues a display switch control signal tothe display switch 48 to switch the connection to couple the display 32,previously connected to the external processor 18, to the tabletprocessor 28.

Thus, the tablet computer 10A of the embodiment of FIG. 3B is alsocapable of automatically transitioning into and out of monitor modebased on detected statuses of the video-in link and the data link withthe external processor 18. Other transitions amongst various modes ofoperation, shown in FIGS. 2A-2D, are also automatically implemented bythe controller 50 based on detected statuses of the video-in link andthe data link with the external processor 18.

As with the previous embodiment of FIG. 3A, in the embodiment of FIG.3B, various other devices 58, 60, 62, and the USB client interface 64may be coupled to downstream ports of the data flow control device 34Ato have their data lines aggregated therein. Unlike the previousembodiment, however, because the two-way switch 68 is arranged betweenthe sensor 30 and the downstream port 43A of the data flow controldevice 34A to thereby control the connection state of only the sensor30, the sensor signal filter comprised of the two-way switch 68 and thedata flow control device 34A does not function to switch the connectionstates of all of these devices and the sensor 30 at the same time. Asillustrated in FIG. 3B, a switch 69A is provided between the USB jack 58and a downstream port of the data flow control device 34A, and a switch69B is provided between the other input/output devices 62 and adownstream port of the data flow control device 34A. The controller 50is operable to issue sensor switch control signals to the switches 69Aand 69B based on the detected statuses of the video-in link and the datalink with the external processor 18, to selectively change the operationmode (e.g., disabled or abled) of the USB jack 58 and the otherinput/out devices 62, respectively.

FIG. 3C illustrates a configuration including the flow control device34, which allows for switching among three operation modes of the sensorbased on a reported video-in link status change, without requiring areport of a data link status change. The flow control device 34 is adevice capable of shutting off a communication flow from its downstreamport to its upstream port when the uplink port 43B is in disconnectedstate, independently and regardless of any control signal from thecontroller 50. In the illustrated embodiment, two types of sensors 30Aand 30B are connected as the sensor 30, to which switches 68A and 68Bare respectively connected. In this example, the controller 50 performsthe following operation: (i) it receives a video-in link status changereport (connected or disconnected) from the video signal detector 40,which has detected whether the video-in link exists or not; (ii) itswitches the switch 48 from IN to EXT (or from EXT to IN), in order tohave the video signal from the external on the display 32; (iii) withoutwaiting for a report of a data link status and using only the detectedvideo-in link status change as a trigger, it switches the switches 68Aand 68B for the sensor 30 from IN to EXT (or from EXT to IN), similar tothe display 32.

When the uplink port 43B of the flow control device 34 is in connectedstate, and when the switches 68A and 68B are switched to EXT, the sensor30A/30B can output the positional input signal to the external processor18. When the uplink port 43B of the flow control device 43 is indisconnected state, because the switches 68A and 68B are both in EXTstate, the positional input signal form the sensor is not output toeither of the processors, i.e., the sensor is disabled.

As shown in FIG. 3C, by using the flow control device 34 capable ofshutting off its traffic flow based on the uplink port status,independently of the controller 50, it is possible to achieve switchingbetween three operation modes of the sensor 30 (30A, 30B) using a 1-to-2switch: EXT, where the positional input signal is communicated to theexternal processor 18; IN, where the positional input signal iscommunicated to the internal processor 28; and DISABLE, where the sensoris unused). Also, switching among the three operation modes is achievedbased only on a detected video-in link status change, without requiringreporting of a data link status, which facilitates implementation with asimpler configuration. Still further, the controller 50, when receivinga report from the video signal sensor 40 that a video-in link isdisconnected, switches the switches 68A, 68B from EXT to IN, withouthaving to wait for reporting of a data link status. Therefore, even whenthe uplink port 43 of the flow control device 34 is connected to theexternal processor 18, without any explicit control from the controller50, based on the connection from the directly connected devices 66 ofthe internal processor 28 to the sensor signal interface 49 of theexternal computer 12 via the flow control device 34, the connectivity tothe directly connected devices 66 such as the storage (or a GPS sensor,Bluetooth® module, etc.) via the USB client component 64 can be ensured.

In other embodiments, the video signal sensor 40 is capable of detectingwhether an external computer is connected, and whether that externalcomputer is sending a video signal or not (the latter, e.g., because theexternal computer went to sleep). In such an embodiment, the controller50 may switch the switch 46 (see FIG. 3A) to connect the sensor 30 andother devices to the external computer 12 if the video connection isestablished and a video signal is provided, or switch the switch 46 toOFF if the video connection is established but no video data is providedby the external computer 12, or switch the switch 46 to connect thesensor 30 and other devices to the internal processor 28 if no videoconnection is established.

FIG. 4 is a block diagram illustrating further embodiments of a tabletcomputer 10B coupled to an external processor 18, wherein the likecomponents and elements are labeled and numbered the same as in theprevious embodiments of FIGS. 3A and 3B. The embodiments of FIG. 4differ from the previous embodiments in that they are specificallyconfigured to be coupled to an external processor 18 via a single cableconnection 20C (e.g., Thunderbolt® cable) or a wireless connection 20D(e.g., Bluetooth®, a USB protocol data encapsulated in frame IEEE802.11a/b/g/n, WiHD™ or similar technology), as shown in FIG. 1B. Also,the external processor 18, to which the tablet computer 10B is coupled,is part of an external computer 12 including at least an input device 16(e.g. keyboard, trackpad or mouse), such as the laptop computer 12A ofFIG. 1B.

In this embodiment, when the tablet computer 10B is coupled to theexternal processor 18 via the single cable connection 20C or thewireless connection 20D, through which all of the lines (e.g., the dataline, the video line, a command line, etc.) are connected ordisconnected at the same time, a user is given the ability toselectively connect or disconnect one or more of these lines to effectoperation mode switching for the tablet computer 10.

An embodiment of the tablet computer 10B using a single cable connectionis first described. The tablet computer 10B includes multiple switches70A, 70B, 70C, 70D . . . , respectively assigned to multiple devices ofthe tablet computer 10B. In the illustrated embodiment, the positionalinput sensor 30 includes a pen sensor 30A and a touch sensor 30B, whichare operable to detect positional input by a pen and a finger to outputa pen input signal and a touch input signal, respectively. The firstswitch 70A is connected to the pen sensor 30A and the second switch 70Bis connected to the touch sensor 30B. The tablet computer 10B may alsoinclude further devices, such as a memory/data storage device 44 orbattery charging circuit or Bluetooth antenna, etc., directly connectedto the processor 28, the data of which the processor 28 may provide tothe external computer 12 via the USB client module 64. Additionalswitches 70C and 70D may be provided for additional devices of thetablet computer 10B, such as the USB jack 58 and the other input/outputdevices 62, respectively, in a similar manner as shown and explained forFIG. 3B.

Each of these switches 70A, 70B, 70C and 70D is provided to selectivelyestablish (or not establish) a data link between the correspondingdevice (the pen sensor 30A, the touch sensor 30B, the USB-connecteddevices 60, and the other input/output devices 62 of the tablet computer10B) and the external processor 18 while the tablet computer 10B iscoupled to the external processor 18 via the single cable 20. Forexample, the first and second switches 70A and 70B may be each comprisedof a three-way switch operable to selectively communicate the positionalinput signal received from the corresponding sensor 30A or 30B to asensor signal interface 72A or 72B (e.g., USB interface) of the externalprocessor 18, the sensor signal interface 47 (e.g., USB interface) ofthe tablet processor 28, or an OFF terminal (i.e., to neither theexternal processor 18 nor the tablet processor 28). The third and fourthswitch 70C and 70D do the equivalent switching for, e.g., the other I/Odevices 62 or USB-connected devices 60, with respect to the interfaces72C and 72D of the external computer 12. Operation states of each ofthese switches 70A, 70B, 70C and 70D are controlled by data switchcontrol signals issued from the tablet processor controller 50.

As in the previous embodiments, the tablet computer 10B also includesthe display switch 48 capable of coupling the display 32 of the tabletcomputer 10B to either the external processor 18 or the tablet processor28 based on a display switch control signal issued from the controller50.

According to some embodiments, a user may semi-automatically controloperation of each of the various devices of the tablet sensor 10Bcoupled to each switch via a user interface (UI) window displayed ondisplay 32 of the tablet computer 10 using the input device 16 of theexternal computer 12. FIG. 4 illustrates the display 32 showing a UIwindow 78 including various user-selectable elements (checkboxes,buttons, or other user-selectable software switches). Theuser-selectable elements are provided to permit user control of each ofthe switches 70A, 70B, 70C, and 70D, i.e., to control the connectionstate of each switch to establish a data link between the correspondingdevice and the external processor 18, or to establish a data linkbetween the corresponding device and the tablet processor 28, or not toestablish a data link with either of the processors 18 and 28 (i.e.,“OFF” state).

In the illustrated embodiment, when the single cable 20 is coupled tothe external processor 18, all of a video-in link 79 and various datalinks 81A, 81B, 81C, 81D, and 81E are established. The data links 81A,81B, 81C, 81D, and 81E are respectively between the pen sensor 30A (viathe switch 70A) and the interface 72A, between the touch sensor 30B (viathe switch 70B) and the interface 72B, between the USB jack 58 (via theswitch 70C) and the interface 72C, between the other input/output device62 (via the switch 70D) and the interface 72D, and between the USBclient 64 and a USB interface 74. Also, the controller 50 establishes acommand link 83 with the external processor 18. For example, thecontroller 50 may establish an Android® Debug Bridge (ADB) link as acommand link through the USB-Client interface connection 64 to theprocessor interface 74, through which the controller 50 may send amessage to and receive a message from the external processor 18. Inaccordance with some embodiments of the present invention, thecontroller 50 sends a mode-switching UI message to the externalprocessor 18. The external processor 18 may then send a video signal todisplay the UI window 78 on the display 32 of the tablet computer 10based on the received mode-switching UI message, according to anystandard message passing system or protocol such as MPI. When a usermakes entry in the UI window 78 using the input device 16 of theexternal computer 12 (or using the input sensor 30 of the tabletcomputer 10B, if not disabled), the external processor 18 recognizes theuser entry and sends a UI-entry message indicative of the user entry tothe tablet controller 50. The controller 50 interprets the receivedUI-entry message to identify user selection of one or more of theuser-selectable elements, and issues corresponding data switch controlsignals to control the connection states of the switches 70A, 70B, 70C,and 70D. For example, when the received UI-entry message indicates userselection of “PEN” “OFF” state, the controller 50 issues a data switchcontrol signal to the switch 70A to switch its connection state to “OFF”state.

In FIG. 4, the UI window 78 includes the user-selectable elements thatallow a user to select between two operation modes for the “PEN” sensor30A and the “TOUCH” sensor 30B. The two operation modes are to establishor maintain a data link with the external processor 18 such that thesesensors are available for the external processor 18 (“ON”), or to notestablish or maintain a data link with either the external processor 18or the tablet processor 28 to essentially disable these sensors (“OFF”).With the video-in link 79 maintained, user selection of the “ON” elementresults in desktop mode of operation and user selection of the “OFF”element results in monitor mode of operation, as previously described.

As apparent from the above examples, the meaning of each of theuser-selectable elements may vary depending on each device and eachapplication. Also, there may be one, two, or three operation modesprovided for a user based on a two-way switch or a three-way switchassociated with a particular device of the tablet computer 10B. Byselectively activating various user-selectable elements on the UI window78, the user may cause the tablet computer 10B to switch between variousoperation modes. For example, an operation mode in which the user hasturned “ON” only the “PEN” sensor 30A and the “OTHER I/O DEVICES” (e.g.,“CAMERA & MIC”) device 62, as shown in FIG. 4, is different from anoperation mode in which the user has turned “ON” only the “TOUCH” sensor30B. Based on a combination of various user-selectable elements, as wellas particular selection states of the user-selectable elements in eachapplication, various operation modes may be realized for the tabletcomputer 10B. That is, the operation modes of the tablet computer 10Bmay switch semi-automatically based on user selection of a particularset of the user-selectable elements (UI software switches) on the UIwindow 78.

As shown in FIG. 4, the UI window 78 may therefore display on thedisplay 32 an indicator of an operation mode selected by the user. Forexample, the UI window 78 may indicate “PEN” sensor 30A “OFF”corresponding to monitor mode when the video-in link 79 is maintained.As another example, the UI window 78 may indicate “CAMERA & MIC” “ON” toindicate an operation mode in which the external processor 18 may accessthe tablet computer's other I/O devices 62.

In both monitor mode and desktop mode, the display displays a videosignal provided from the external processor and, therefore, a user maynot be readily distinguish between the two modes. Then, the command link83 may be used by the tablet controller 50 to send a message to theexternal processor 18, to cause the external processor 18 to send “back”a video signal including an operation mode indicator to the tabletdisplay 32 via the video-in link 79. For example, when the video-in link79 exists but no data link exists, an indicator indicative of monitormode may be sent to the tablet display 32. This indicator notifies theuser that the input sensor 30 is not operable and the tablet computer 10is functioning as a monitor for the external processor 18.

Thus, the tablet computer 10B of the present embodiment is capable ofallowing a user to selectively place any of the devices of the tabletcomputer 10, such as the pen sensor 30A, the touch sensor 30B, the otherI/O devices 62 or the USB-Jack 58 and USB-connected devices 60, incommunication with the external processor 18 under control of theexternal processor's OS, or in communication with neither of theprocessors (i.e., disabling them).

The embodiment of the tablet computer 10B of FIG. 4 may also beimplemented using a wireless connection 20D to couple the tabletcomputer 10B to the external processor 18. The wireless connection 20Dmay be, for example, a connection pursuant to Bluetooth®, a USB protocoldata encapsulated in frame IEEE 802.11a/b/g/n, WiHD (WirelessHD™) orsimilar technologies. The tablet computer 10B includes a suitablewireless connection circuit 80 to prepare wireless signals to betransmitted, via an antenna 82, to the external computer 12, which iscorrespondingly equipped with a suitable wireless connection circuit andan antenna.

FIG. 5A is a flowchart illustrating an example process of switchingoperation modes of a tablet computer coupled to an external processor,according to one embodiment of the present invention. The methodincludes generally three steps: (i) detecting a video-in link status ofthe tablet computer from a separate external processor (block 83); (ii)detecting a data link status of the tablet computer relative to theseparate external processor (block 84); and (iii) when the video-in linkexists but the data link does not exist relative to the separateexternal processor, displaying a video signal from the separate externalprocessor on a tablet display and not communicating the positional inputsignal from a tablet sensor to either the tablet computer processor orthe separate external processor (block 85).

FIG. 5B is a flowchart illustrating another example process of switchingoperation modes of a tablet computer coupled to an external processor,according to another embodiment of the present invention. The processincludes generally two steps:

STEP I—detecting a video-in link status of the tablet computer from aseparate external processor (block 83A), and

STEP II—using a change in the detected video-in link status as atrigger, and based on a data link status, switching between threeoperation modes of the sensor including (EXTERNAL), wherein thepositional input signal is communicated to the external computer;(INTERNAL), wherein the positional input signal is communicated to theinternal processor; and (DISABLE), wherein the sensor is unused (block84A).

FIG. 5C is a diagram illustrating twelve transitions amongst fouroperation modes of a sensor. In FIG. 5C, the number following “USB”indicates the data link interface status. “1” indicates a data link withthe external processor 18 and “0” indicate no data link. Also, thenumber following “HDMI” indicates the video-in link interface status.“1” indicates a video-in link with the external processor 18 and “0”indicates no video-in link. In FIG. 5C, arrow 1 indicates a transitionof a video-in link status from disconnected to connected while a datalink is disconnected. Arrow 2 indicates a transition of a data linkstatus from disconnected to connected while a video-in link isconnected. Arrow 3 indicates a transition of a video-in link status fromconnected to disconnected while a data link is connected. Arrow 4indicates a transition of a data link status from connected todisconnected while a video-in link is disconnected. Arrow 5 indicates atransition of a data link from disconnected to connected while avideo-in link is disconnected. Arrow 6 indicates a transition of avideo-in link status from disconnected to connected while a data link isconnected. Arrow 7 indicates a transition of a data link from connectedto disconnected while a video-in link is connected. Arrow 8 indicates atransition of a video-in link from connected to disconnected while adata link is disconnected. Arrows 9-12 respectively indicatecombinations of two of the transitions 1-8 at the same time, wherein thestatuses of both interfaces (USB and HDMI) are changed.

FIG. 5D indicates various transitions to switch amongst three operationmodes of a sensor, which may be implemented by the controller 50 in STEPI (block 83A) of FIG. 5B. In FIG. 5D, the number(s) placed adjacent toeach transition arrow indicates input for each transition, and thenumber corresponds to the transitions 1-12 detailed above in referenceto FIG. 5C. If transition (status change) 1 is provided as input to thecomputer 10, which is a transition of a video-in link status fromdisconnected to connected while a data link is disconnected, thecontroller 50 executes control so as to render the sensor 30 in anunusable state (DISABLE). Such control may entail disabling a devicedriver of the sensor 30 as described above, or may entail use of theflow control device 34 as shown in FIG. 3C to independently cut off theflow of the positional input signal from the sensor 30. When transition(status change) 8 is detected, the controller 50 transitions the sensor30 from the unusable state (DISABLE) to a state at which the sensor 30is controlled by the internal processor 28 (INTERNAL), i.e., into mobilemode.

If transition (status change) 2 is detected as input, wherein a datalink status is transitioned from disconnected to connected while avideo-in link is connected, the tablet computer 10 switches theoperation modes of the sensor 30 from DISABLE to EXTERNAL. In transition(status change) 7, wherein a data link status is transitioned fromconnected to disconnected while a video-in link is connected, the tabletcomputer 10 switches the operation modes of the sensor 30 from EXTERNALto DISABLE. These switching operations may be executed by the controller50.

While transitions 1 and 8 require control by the controller 50,transitions 2 and 7 may be realized based on the independent operationof the flow control device 34 described above in reference to FIG. 3Cwithout requiring control from the controller 50.

Thus, a video-in link status signal, which has been used to triggerswitching of operation modes of the display 32, is used also as atrigger to switch operation modes of the sensor 30, according to variousembodiments of the present invention. Further, because the sensor 30 isdisabled in correspondence to what is displayed on the display 32, anundesirable situation can be avoided, such as that a user attempts tooperate the sensor 30 coupled to the internal processor 28 while viewingthe display 32 displaying a video signal from the external computer 12.

In each of the transitions as shown in FIG. 5D (or 5C), a definedprocess specific to each transition can be carried out by thecontroller. For example, in transition (status change) 7 of switchingfrom desktop mode to monitor mode, after detecting a video-in linkstatus (STEP I of FIG. 5B) and before switching the operation mode basedon the detected video-in link status as a trigger (STEP II of FIG. 5B),a suitable command may be issued to display a UI indication on thedisplay to assist a user to distinguish between monitor mode and desktopmode. As another example, in transition (status change) 9 of switchingfrom mobile mode to desktop mode, internal unnecessary processes, suchas the process concerning a device driver for the sensor and a WirelessLAN related process, may be disabled so as to decrease battery/powerconsumption. As a further example, also in transition 9 of switchingfrom mobile mode to desktop mode, after the transition is completed, thelatest file edited by the application on the internal processor may beuploaded to be editable by the external processor.

FIG. 6 is a flowchart illustrating another example process of switchingoperation modes of a tablet computer coupled to an external processor,suitable for execution in a tablet computer coupled to an externalprocessor wirelessly or via a single cable such as the tablet computer10B described above in FIG. 4. The process includes generally six steps:(i) establishing a video-in link between the tablet computer (the tabletdisplay) and a separate external processor (block 86); (ii) establishinga data link between at least one of the sensor section 30 and the one ormore devices (e.g., 60,62) of the tablet computer and the externalprocessor (block 87); (iii) establishing a command link with theseparate external processor (block 88); (iii) sending a mode-switchinguser interface (UI) message to the separate external processor via thecommand link to cause the separate external processor to display amode-switching UI on the tablet display, the mode-switching UI includingat least one user-selectable element to control operation of at leastone of the sensor section and the one or more devices of the tabletcomputer (block 89); (iv) receiving user selection of the at least oneuser-selectable element on the tablet display, made via an externalinput device coupled to the separate external processor (or via thesensor section, if not disabled), as a UI-entry message from theexternal processor via the command link (block 90); and (v) controllingoperation of the corresponding device based on the received UI-entrymessage (block 91).

The various embodiments described above can be combined to providefurther embodiments. These and other changes can be made to theembodiments in light of the above-detailed description. In general, inthe following claims, the terms used should not be construed to limitthe claims to the specific embodiments disclosed in the specificationand the claims, but should be construed to include all possibleembodiments along with the full scope of equivalents to which suchclaims are entitled. Accordingly, the claims are not limited by thedisclosure.

The invention claimed is:
 1. A mobile tablet computer, comprising: asensor section operable to detect positional input by a human operatorand output a positional data to an interface; a display, arranged sothat the sensor section and the display form a stack, operable toreceive, through a display interface, a video signal and display thevideo signal; and an internal processor, coupled to a memory storingprograms for running an operating system (OS) and executing softwareloaded to the memory, the internal processor being operable to: (i)responsive to a detected first link status indicating the interface isconnected to an external computer, control the mobile tablet computer,as a human interface device of the external computer, to input thepositional data via the interface to the external computer; and (ii)responsive to a detected second link status indicating the interface isnot connected to the external computer, control the mobile tabletcomputer, as a host computer, based on the position data.
 2. The mobiletablet computer of claim 1, wherein the internal processor is operableto receive and process the position data from the sensor section and tooutput the video signal of the OS and the software to the display. 3.The mobile tablet computer of claim 1, wherein the interface is auniversal serial bus (USB) interface.
 4. The mobile tablet computer ofclaim 1, comprising: one or more switches, operable to: connect theinterface and the display interface to the external computer in a humaninterface device mode; and connect the interface and the displayinterface to the internal processor in a host computer mode.
 5. Themobile tablet computer of claim 4, wherein, the one or more switches, inthe human interface device mode, do not supply the positional data tothe internal processor.
 6. The mobile tablet computer of claim 4,wherein switching between the human interface device mode and the hostcomputer mode is based at least on a video-in link status of the mobiletablet computer relative to the external computer.
 7. The mobile tabletcomputer of claim 6, wherein the video-in link status is a logical stateof the video interface capable of communicating the video signal fromthe external computer to the display.
 8. The mobile tablet computer ofclaim 4, wherein switching between the human interface device mode andthe host computer mode is based at least on a logical state of theinterface.
 9. The mobile tablet computer of claim 4, wherein, in thehuman interface device mode, the display displays the video signal fromthe external computer, and in the host computer mode, the displaydisplays the video signal of the OS and the software.
 10. The mobiletablet computer of claim 9, wherein, in the host computer mode, thedisplay displays the video signal of the OS and the software in which acursor is placed at a position of the positional data.
 11. The mobiletablet computer of claim 1, comprising: one or more switches, operableto: connect the interface to the external computer in a human interfacedevice mode; and connect the interface to the internal processor in ahost computer mode.
 12. The mobile tablet computer of claim 11, whereinthe display is disabled in the human interface device mode.
 13. Themobile tablet computer of claim 11, wherein, the one or more switches,in the human interface device mode, do not supply the positional data tothe internal processor.
 14. The mobile tablet computer of claim 11,wherein switching between the human interface device mode and the hostcomputer mode is based at least on a video-in link status of the mobiletablet computer relative to the external computer.
 15. The mobile tabletcomputer of claim 14, wherein the video-in link status is a logicalstate of the video interface capable of communicating the video signalfrom the external computer to the display.
 16. The mobile tabletcomputer of claim 11, wherein switching between the human interfacedevice mode and the host computer mode is based at least on a logicalstate of the interface.
 17. The mobile tablet computer of claim 11,wherein, in the host computer mode, the display displays the videosignal of the OS and the software in which a cursor is placed at aposition of the positional data.